Circuit breaker



1947- H. s. GANO ETAL CIRCUIT BREAKER Filed Sept. 15, 1942 2 Shuts-Shoot 1 2 m 3 a 9 $8 5 v :6 9%- 5 .m I n... 5 y u 1 1 m 3 2m 2 (i K m 1 j] a nun 91 INVENTORS Harlan 5. Gano and Gerald J Freese. a BY ATTORNE Feb. 18, 1947. HLSFGANQ ETAL 2,416,170

gmwu'rr n mmma ji'iled Sept. 15, v19 42 2 Shoots-Shoot 2 INVENTQRS WITNESSES: v

Harlan 5 Garza and Patented Feb. 18, 1947 CIRCUIT BREAKER Harlan S. Gano, Wilkinsburg, and Gerald J. Freese, East McKeesport, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 15, 1942, Serial No. 458,390

26 Claims. (Cl. 200-116) The invention relates to circuit interrupters and more particularly to circuit breakers for controlling lighting circuits and small to moderate power low voltage circuits.

An object of the invention is the provision of an improved circuit breaker of the class described that is very simple and compact, accurate and reliable in operation and economical to manufacture.

Another object of the invention is the provision of a circuit breaker embodying an improved snapaction operating mechanism that is manually operable to open and close the breaker and that is adapted t be tripped by a current responsive trip element in response to predetermined overload conditions to cause automatic opening of the contacts.

Another object of the invention is the pro-t vision of a circuit breaker with an improved operating mechanism as previously described wherein the breaker may be manually closed or held closed against an overload current condition in the circuit.

Another object of the invention is the provision of a circuit breaker with an improved operating mechanism having an operating lever that is manually operated to produce opening and closing of the breaker and a spring biased lever releasable to cause the mechanism to automatically open the breaker, and a link providing lost motion connection between the two levers whereby it is possible for the operator to close and hold the breaker closed against an overload in the circuit.

Another object of the invention is the provision of a circuit breaker with an improved operating mechanism as described in the preceding paragraph, wherein the breaker can be made trip free of the operating handle by eliminating one of the elements of the mechanism, namely, the aforementioned connecting link.

Another object of the invention is the provision of a circuit breaker with an improved operating mechanism wherein the mechanism after it is tripped can be reset to operative condition by moving the operating handle as far as it will go in an oii direction, or the mechanism can be reset and the contacts closed at the same time by simply moving the handle to the on position.

Another object of the invention is the provision of a circuit breaker of improved construction wherein the cover of the casing is made up of two metal plates so formed and spaced as to provide a pivot and support for the external operating handle.

Another object of the invention is the provision of a circuit breaker embodying an improved operating mechanism having an internal operating lever that is separably engaged by an external handle lever mounted on the removable cover of the breaker housing.

Another object of the invention is the provision of a circuit breaker as previously described wherein a positive indication is given that the breaker has been tripped open.

Another object of, the invention is the provision of a circuit breaker with an improved thermally responsive trip device operable to trip the circuit breaker in response to overload current conditions and which is fully compensated in a novel manner for changes in ambient temperature over a wide range.

Another object of the invention is the provision of a circuit breaker with an improved thermally responsive overload trip device that provides an mproved automatic operating characteristic to afford a greater time delay action on overloads of low magnitude than many prior art thermal circuit breakers, and yet which also provides the desired quick response on heavy overloads and short circuits.

These and other objects and advantages of the invention, together with the detailed structure and mode of operation thereof, will be best understood from the following detailed description-of several embodiments of the invention when read in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a circuit breaker constructed in accordance with the invention, the breaker being shown in the closed circuit position;

Fig. 2 is a horizontal sectional view of the circuit breaker, the section being taken substantially along the line 11-11 of Fig. 1;

Fig. 3 is a sectional View similar to Fig. 1 but showing the breaker in the manually open or off position;

Fig. 4 is a sectional view similar to Fig. 1 but showing the breaker in the tripped open position;

Fig. 5 is a vertical sectional view of a modification of the circuit breaker wherein a modified shape or release lever has been substituted so that the operating handle will indicate tripping of the breaker; a slightly modified connection between the bimetal elements is also illustrated in this figure;

Fig. 6 is a vertical sectional view similar to Fig. 5 but showing a further modification of the breaker wherein the handle connecting link has been eliminated to make the breaker trip free of the handle; this view and Fig. both showing the breaker in tripped position; and

Fig. 7 is a perspectiveview of one of the lock nuts for the mounting screws which secure the breaker to a panel.

Referring to Figs. 1 to 4 of the drawings, the circuit breaker includes a rectangular base 9 of insulating material upon which is mounted a pair of terminal members H and I3, the circuit breaker mechanism frame l5, and an overload current responsive trip device l1.

The upper terminal member H is securely clam -ed to the back of the base 9 by a contact supporting bracket l9 of conducting material, which has an enlarged portion disposed on the front side of the base inside the circuit breaker casing, and a reduced portion that. extends through openings provided therefor in the base 9 and terminal member I I. The shoulder provided by the enlarged portion of the bracket l9 bears against a metal washer 2|, and the end of the reduced portion of the bracket is clenched or riveted over against the terminal member i I, thereby rigidly clamping the terminal member and the contact bracket in mounted position on the base 9. The lower terminal member I3 is secured to the back of the base 9 in a similar manner by a bracket 23 of conducting metal that has a flat portion bearing against the front of the base 9, and two rearwardly extending projections 25 and 21 that pass through openings in the base 9. The projection 25 also passes through an opening in the terminal member l3 and the end thereof is riveted over against the terminal member. The other projection 27! has its end riveted over against a metal washer 29. The bracket 23 has forwardly extending ears 3! which serve to pivotally support the current responsive trip element of the trip device ll that will be described hereinafter.

The circuit breaker mechanism supporting frame comprises a pair of angle shaped flat metal plates 33 which are mounted in spaced parallel relation on the front side of the base 9. Each side plate has a reduced portion that passes through an opening in the base 9 and the end of this reduced portion passes through a metal washer and is clinched or riveted over against the washer to securely clamp the plate in mounted position on the base 9. The frame also includes an end plate 35 located adjacent the upper end of the base 9 and securely clamped to the base in a similar manner by having a reduced portion projecting through the base and riveted over against a metal washer. The ends of the upwardly extending portions of the side plates 33 are riveted to the opposite side edges of the end plate 35 to thereby form a rigid frame structure.

A rectangular metal casing 31 is provided for enclosing the circuit breaker mechanism. This casing surrounds the circuit breaker mechanism and is secured to the insulating base 9 by a plurality of lugs 39 on the casing that are bent over the side edges of the base 9 to clamp the casing to the base. A cover 4! consisting of two preformed metal plates 43 and 45 that are riveted together by rivets 41 and 49, is mounted on the front of the casing to complete the enclosing housing of the breaker. The cover M is secured to casing 31 by a plurality of lugs 5i (Fig. 2) on the front edge of the casing, that are bent over the inner plate 43 of the cover. An insulating lining 38 is disposed around the entire inner sursupporting lever 67.

face of the casing 31 to insulate the metal casing from the mechanism.

The circuit breaker is adapted to be mounted on a panel 53 by means of a pair of screw bolts 55 which threadedly engage a pair of special lock nuts 51 that are disposed and retained in spaces provided therefor between the opposite ends of the cover plates 43 and 45. One of the special lock nuts is .-hown in Fig. 7.

The circuit breaker includes a stationary con tact 6| mounted on the contact bracket l9, and a cooperating movable contact 63 secured to the end of a movable contact member or switch member 65 of conducting material adapted to be operated with a snap action to open and closed circuit positions by the circuit breaker operating mechanism, to open or close the circuit breaker contacts. The circuit breaker operating mechanism can be manually operated to effect opening or closing of the contacts and is also adapted to be operated automatically by the trip device to effect automatic opening of the contacts in response to predetermined overload current conditions in the circuit.

The operating mechanism comprises, in general, a pivotally mounted releasable supporting lever 61 on which the switch member 65 is pivotally mounted for oscillation, a pivoted operating lever 69, an external operating handle H operatively engaging the operating lever, and a pair of overcenter operating springs 73 operatively connecting the operating lever 69 to the movable switch member 65. The releasable supporting lever 6'! is pivotally supported on the frame [5 between the sides thereof by a pivot pin 15, and this lever has a relatively deep V-shaped notch H therein for receiving the movable switch member 65. The outer end of the switch member 65 has a slot therein which pivotally engages the apex 18 of the V-shaped notch 11 to thereby pivotally mount the switch member on the releasable The supporting lever 61 is normally held latched in the fixed position shown in Figs. 1 and 3 by a latch of the trip device I! which normally engages a latch surface on the lower free end of the lever 61 to hold the lever in this position.

The operating lever 69 consists of two legs or levers 19 (Fig. 2) which are rigidly secured together in spaced parallel relation by a cross pin 8| rigidly connecting the outer ends of the levers. The inner ends of the legs 19 are generally segmental in shape and are pivotally engaged in correspondingly shaped pivot bearing recesses provided therefor in the side plates of the frame I5, whereby the operating lever is pivotally mounted for oscillation on the frame. The legs of the operating lever are inserted in the bearing recesses in the frame by pushing them sideways into these recesses, lateral displacement of the operating lever being prevented by the sides of the casing after the casing 31 is assembled on the base 9. Notches 83 provided in the sides of the frame l5 limit opening and closing movement of the operating lever'69.

The two overcenter operating springs '13 are disposed on opposite sides of the releasable lever 61 and the switch member 65, the outer ends of these'springs being connected to the operating lever 69 by engaging slots provided in the cross pin 8| of the operating lever. The inner ends of the springs '13 are connected to lateralprojections formed on opposite sides of the switch member 65 as shown in Fig. 2.

The external operating handle 1| comprises a metal lever having a generally spherical portion 85 by means of which it is pivotally mounted for oscillation on the cover M of the circuit breaker. The two plates 43 and 45 comprising the cover are formed to provide a pivot bearing for the spherical portion 85 of the operating handle. The inner plate 43 is provided with a cylindrical opening 81 against which the inner portion of the spherical portion of the handle bears, and the outer plate is slightly spaced from the inner plate opposite the circular opening 81, and this portion of the plate 45 is provided with an oval-shaped opening bounded by edge portions which are spherically shaped to engage and conform to the shape of the spherical portion '5 of the external operating handle. The sphe ical portion of the handle is retained in mounted position between the two plates in the bearing provided therefor, and this handle is manually movable back and forth between on and off positions for operating the mechanism to cause closing and opening of the circuit breaker contacts. The portion of the handle II which projects inside of the casing has an insulating block 8| secured thereto as by a rivet, and this block is provided with a transverse slot.93 which is adapted to engage the cross pin 8| of the operating lever 69 whereby the operating handle II is operatively connected to the operating lever 69 when the casing and cover are assembled on the base 9. Movement of the operating handle II upwardly to the off position moves the operating lever 69 downwardly to "off or open position to effect opening of the circuit breaker contacts. Conversely, when the operating handle II is moved downwardly to the "on position, it effects movement of the operating lever 69 upwardly to "on or closed position to eflect closing of the circuit breaker contacts.

A connecting link 95 is provided between the operating lever 69 and the releasable supporting lever 61. This link is in the form of a double link which pivotally engages the cross pin 8| of the operating lever 69 at one end, and the other end of the link carries a pin 91 which engages and moves in an elongated slot 99 provided therefor in the releasable supporting lever 61. During normal manual operation of the circuit breaker to opened and closed position, the slot 99 permits movement of the operating handle 1| and operating lever 69 to on and off positions while the releasable-supporting lever 61 is restrained in the fixed position shown in Figs. 1 and 3. When the operating handle II is in the on" position shown in Fig. 1, the pin 91 carried by the link 95 engages the inner end of the slot 99, so that it is possible for an operator to hold the circuit breaker closed by holding the operating handle in the on position shown. When the handle is thus held in the on position, it acts through the link 95 to prevent tripping operation of the releasable supporting lever 61 even though the current responsive trip device may have released the lower end of the supporting lever 61. Under these conditions, the link 95 acts to hold the releasable supporting lever 61 in the fixed position shown. The link 95 also provides a means whereby the circuit breaker mechanism may be reset andthe contacts operated to the closed position simply by moving the operating handle to the .on position following a tripping operation of the breaker.

The trip device I! of the circuit breaker comprises a current responsive bimetal trip element lI formed of a flat strip of bimetallic material which is secured at its inner end to the shank portion of a metal connecting lever I03. The shank portion of the metal connecting lever I03 is pivotally mounted by a. pivot pin I05 on the ears 3I of the bracket 23. The outer free end of the connecting lever I03 is bent and provided with a slot through which it engages the free end of an ambient temperature compensating bimetal element I01. The inner end of the ambient temperature compensating bimetal strip I0! is bent angularly and is clamped against the base 9 of the circuit breaker by means of a bracket I09. The bracket I09 has a reduced portion which extends through an opening provided therefor in the angularly bent foot of the bimetal strip I01 and passes through an opening in the base I. The end of the reduced portion of the bracket I09 is riveted over against a metal washer on the rear side of the base 9, thereby securely clamping the ambient temperature responsive bimetal element in mounted position on the base 9. The outer free end of the current responsive bimetal trip element IOI has a U-shaped element III rigidly secured thereto and a latch I I3 is, in turn, rigidly secured to this U-shaped element on the free end of the bimetal element IOI. During normal conditions, the latch H3 is adapted to engage the free end of the supporting lever 81 to hold this lever in the fixed position shown in Figs. 1 and 3. The bimetal trip element is adapted to be heated in response to overload current in the circuit controlled by the breaker and when heated a predetermined amount, it deflects in a downward direction to cause the latch H3 to disengage and reelase the supporting lever 61 to thereby cause the mechanism to effect automatic opening of the circuit breaker contacts.

A flexible shunt conductor I I5 electrically connects the switch member and movable contact 63 to the outer free end of the bimetal trip element WI. The inner end of this trip element is electrically connected by a resilient copper strip I I! to the lower terminal bracket 23 and hence to the lower terminal member I 3. The circuit through the breaker extends from the upper terminal member II through the contacts BI and B3, switch member 65, flexible shunt conductor H5, connecting element III, current responsive bimetal trip element IOI, conducting strip II! and bracket 23 to the lower terminal member I3.

The ambient temperature compensating bimetal element I0! is disposed to deflect in an opposite direction to that of the current responsive bimetal element IOI when the elements are heated by ambient temperature, so as to compensate the breaker for changes in ambient temperature. When the ambient temperature increases, the bimetal element I01 deflcts in an upward direction to compensate for the corresponding downward deflection of the trip element IOI produced by ambient temperature. Conversely, when the ambient temperature decreases, the ambient temperature responsive bimetal element I01 deflects downwardly to compensate for the corresponding upward deflection produced in the bimetal trip element IN by the change in ambient temperature. Consequently, the trip device is made responsive only to overload currents and is unaffected by changes in ambient temperature. Adjustment of the minimum overload current trip setting at which the trip device will operate to trip the breaker is effected by means of an adjusting screw H9. The adjusting screw it? and the body of the screw is threadedly engaged in an opening provided in the mounting bracket )9. The lower end of the screw is provided with a slot which. is disposed opposite an opening in the lower end wall of the casing to permit adjustment of the trip characteristic from outside of the circuit breaker casing. Turning the screw in a coun-r-clockwise direction will effect clockwise rotation of the current responsive bimetal element mi about the pivot Hi and will decrease the minimum amount of overload current necessary to ultimately effect operation of the trip device. Turning the screw in a clockwise direction effects movement of the bimetal trip element Illl in a counter-clockwise direction and will increase the minimum overload current necessary to effect operation of the trip device. Due to the fact that the connecting lever N13 is of metallic material, a small amount of the heat produced in the bimetal trip element ma by relatively low magnitude overload currents will be transmitted to the ambient temperature responsive bimetal element I01, and will thereby cause a greater time delay before the breaker is tripped in response to relatively low overload magnitude currents than would be the case if the two bimetal elements were completely heat insulated from one another. However, on moderate overloads and heavy overloads, little or none of the heat produced in the bimetal element I0! is transmitted to the ambient temperature responsive bimetal element in! since there is insufficient time for a transfer of heat to take place through the metal connecting lever Hi3. Consequently, the bimetal trip element iii! has substantially the same operating characteristic for moderate overloads and high overloads as an uncompensated bimetal element of the same composition. This is a desirable feature of the construction since it provides a greater time delay action on the relatively low magnitude overloads before the breaker is tripped. These low magnitude overloads are not necessarily harmful and may be allowed to persist for a longer time without producing any damage in the control circuit.

A trip indicating button NE of insulating material is provided for indicating when the breaker has been tripped in response to an overload current condition. The trip indicating button 52! is slidably mounted in the cover H of the circuit breaker casing by means of the rivet 49 which is of hollow or eyelet construction. indicating button IN is biased by a spring 823 to a non-indicating position. The spring is disposed upon the shank of the indicating button between the enlarged inner end thereof and the rivet 49. When the circuit breaker is tripped in response to operation of the trip device H, the supporting lever 67 is released and moved outwardly, that is, in a counter-clockwise direction about its pivot to a tripped position. The lower free end of the lever when so moved engages the trip indicating button l2! and moves the same outwardly to a trip indicating position as shown in Fig. 4.

The operation of this embodiment of the circuit breaker is briefly as follows. To open the circuit breaker, the operating handle II is moved upwardly to the oil position shown in Fig. 3. This movement of the operating handle moves the operating lever 69 downwardly in a clockwise direction about its pivot axis to the open position shown in Fig. 3. During this movement. the line of action of the overcenter springs is shifted downwardly below the pivot axis 18, of the switch mem- The trip 1 ber, and as soon as it crosses below the pivot axis 18 the springs actuate the switch member 55 to the open circuit position shown in Fig. 3 with a snap action. In this position, the line of action of the springs is also below the pivot axis of the operating lever 69 so that the springs act to maintain the operating lever and the operating handle in the off position.

To manually close the circuit breaker, the operating' handle H is moved downwardly to the on" position shown in Fig. 1. This movement is transmitted to the operating lever 69 moving the same upwardly to the on position. The line of action of the overcenter spring 13 is shifted above the pivot axi E8 of the switch member 65. As soon as the line of action of the springs moves above the pivot axis 18, the springs operate the switch member 65 to closed circuit position with a snap action. In this position, the line of action of springs is also disposed above the pivot axis of the operatin lever 69 so that the springs maintain the operating lever and operating handle in the on position. The springs also maintain a predetermined high contact pressure between the contacts Bi and 63. The springs always act to bias the releasable supporting lever 61 in a counter-clockwise direction about its pivot 15. However, this member is normally restrained against tripping movement by the latch of the trip device l1.

When an overload current above the minimum trip setting of the breaker occurs in the circuit controlled thereby, the current responsive bimetal trip element tilt is heated by the overload current and after it has been heated a predetermined amount, this element deflects downwardly, causing the latch H3 to release the supporting lever 61, whereupon the operating springs 13 actuate the supporting lever 61 in a counter-clockwise direction about its pivot 15 to the tripped position shown in Fig. 4. Durin the initial por tion of the movement of the supporting lever 61, the upper edge of the V-shaped notch engages the switch member 65 and moves the switch member 65 along with the supporting lever 61 to open position. The tripping movement of the supporting lever 61 also acts through the connecting link to move the operating handle and operating lever 69 toward off position. At a predetermined point during the movement of the supporting lever 6'! toward its tripped position, the line of action of the overcenter spring 13 is shifted below the pivot 18 of the switch member, thereby causing the switch member 65 to be moved to the open position shown in Fig. 4 with a snap action. The line of action of the springs is also shifted below the pivot axis of the operatiiig lever 69 so that the springs act to move the operating lever 69 and the operating handle H quickly to the oil position as shown in Fig. 4.

To reset the circuit breaker mechanism and reclose the contacts of the breaker after an overload tripping operation, the operating handle H is moved from the off position shown in Fig. 4 back to the on position shown in Fig. 1. This movement of the operating handle acts through the link 95 to reset the supporting lever 61 back to its latched position where it is reengaged by the latch N3 of the trip device. This movement of the operatinghandle also and at the same time moves the operating lever "19 upwardly to the on position, thereby causing the operating springs 73 to move overcenter and close the contacts with a snap action. By reason of the link 95,, it is possible for an operator to close the circult breaker contacts and hold the contacts closed against an overload condition in the circuit controlled by the breaker. This may be desirable under certain conditions, such as when it is necessary to prevent interruption of the circuit even though an abnormal current may be present when the circuit is closed. It will be noted that the link 95 has a projection 96 on the inner end thereof. The purpose of this projection is to positivel initiate opening movement of the movable contacts 63 and switch member 65 during both manual and automatic operation of the circuit breaker in order to'insure that the mechanism will carry out the opening operation of the contacts even though the contacts may tend to stick or adhere together. Any sticking or slight welding of the contacts is broken by the positive prying action of the projection 96 on-the inner end of the connecting link 95.

If it is desired to make the circuit breaker trip free of the operating handle, all that is necessary to be done is to omit the connecting link 95 and provide a resetting projection on the supporting lever 61, similar to the resetting projection shown in the Fig. 6 modification, which will be described hereinafter.

A modification of the invention is shown in Fig. 5. The main elements of the circuit breaker structure shown in Fig. are essentially the same as those of the original embodiment of the invention except that the releasable supporting lever for the contact arm is made of a difierent shape so as to cause the operating handle to assume an intermediate indicating position when the breaker has been tripped, thereby eliminating the necessity of a trip indicating button such as disclosed in Fig. l. The modified shape of thereleasable supporting lever also permits this lever; to be reset to the latched position by moving the breaker operating handle to the fofi position. after a tripping operation. A slightly modi' fled form of trip device is also shown in Fi 5. Those elements and parts of the circuit breaker structure shown in Fig, 5 that are identical to the corresponding elements shown in the original embodiment are indicated by the same reference characters.

Referring to Fig. 5, the releasable supporting lever I25 in this embodiment is generally similar to the releasable supporting lever 61 of the original embodiment except that the lever I25 is provided with a cam-shaped projection I21 which cooperates with the cross-pin -BI of the operating lever 69. The releasable lever I25 is pivoted on the frame I5 by means of the pivot pin 15, and has a V-shaped notch for receiving and. pivotally supporting the switch member 65 in the same manner as in the original embodiment previously described. The operating handle TI is movable to "off and on positions to cause the mechanism to effect opening and closing of the circuit breaker contacts with a snap action in the same manner as in the original embodiment previously described. The operating handle H is movable to off and on positions to cause the mechanism to effect opening and closing of the circuit breaker contacts with a snap action in the same manner as in the case of the original embodiment. When an overload current above the minimum trip setting of the breaker occurs in the circuit controlled thereby and persists for a sufiicient length of time to heat the bimetal trip element IOI a predetermined amount, this bimetal element deflects downwardly, causing the latch II3 to disengage the lower free end of the supment of the handle to porting lever I25, thereby releasing the supporting lever. Upon release of the supporting lever I25, the operating springs 13 move this lever in a counter-clockwise direction about its pivot 15 to the tripped position shown in Fig. 5. During the initial tripping movement of the releasable supporting lever I25, the upper edge of the V-shaped notch thereof picks up the contact member 65 and moves it along with the lever and at the same time the projection 96 on the lever also engages and initiates opening movement of the switch member toward open position. At a predetermined point in the movement of the lever I25, the line of action of the operating springs 13 is shifted below the pivot axis 18 of the switch member 65, whereupon the springs move the switch member to open position with a snap action. The link 95 also moves the operating handle 1I toward the off position, this movement being continued by the operating springs as soon as the line of action of the springs shifts below the pivot axis of the operating lever 59, In this embodiment, however, the projection I21 of the releasable lever moves into the path of the cross-pin SI of the operating lever 69 and arrests the opening movement of the operating lever and operating handle II in an intermediate position as shown in Fig. 5 whereby the operating handle II indicates that the breaker has been tripped by an overload.

,After the breaker has been tripped in response to an overload, the breaker may be reclosed and the mechanism reset by moving the operating handle II from the position shown in Fig. 5 downwardly back to the on position. This movethe on position acts the connecting link 95 to reset the suplever I25 back to its latching position through porting where it device. At the same time, this movement of the lever to the on position shifts the line of action of the operating springs above the pivot axis 18 of the switch member the switch member to closed position with a snap action. The mechanism may be reset after tripping without closing the contacts by moving the operating handle II upwardly to the "off position. This movement of the operating handle moves the operating lever 69 downwardly to the "off position and during this movement, the cross-pin BI rides on the surface of the cam projection I21 of the supporting lever, forcing that lever back to its latched position where it is reengaged by the latch II3 of the trip device. In this instance, however, the circuit breaker contacts remain in open position, and after resetting in this manner the circuit breaker may be closed by moving the operating handle back to the on position in the same manner as for normal manual'closing operation of the breaker.

A slightly modified form of ambient temperature compensating arrangement is shown in the Fig. 5 embodiment of the invention. The ambient temperature compensating bimetal element I29 of this embodiment of the invention is secured at its inner end to a supporting bracket I3I which is, in turn, secured to the insulating base 9. An adjusting screw I33 threaded through the ambient temperature bimetal element adjacent the outer end thereof engages the connecting lever I03 and serves to provide for adjusting the minimum overload trip setting of the breaker. A relatively stiff spring I35 connects the free end of the ambient temperature responsive bimetal element I29 to the free end is reengaged by the latch I I3 of the trip 65, causing movement of of the connecting lever I03 and serves to maintain th lever I 03 in contact with the adjusting screw I33. An opening is provided in the lower end wall of the casing to permit adjustment of the screw I33 from outside of the casing. Turnin the screw in a clockwise direction moves the current b metal trip element IiII upwardly about its pivot I05 and increases the minimum overload trip current to which the breaker will respond. Con ersely turning th screw I33 in a counterclock ise direction causes the current bimetal trip element I 03 to be moved downwardly about its pivot and thereby decreases the minimum overload current to which the breaker will respond. In the case of relatively low magnitude overload currents, some of the heat produced in the current bimetal trip element IOI is transmitted to the ambient temperature responsive bimetal element I29 and thereby causes greater time delay action in the case of such relatively low magnitude overload currents than in the case of an uncompensated bimetal trip device. In the case of moderate overload currents and heavy overload currents or short circuits, substantially no heat is transferred to the ambient temperature responsive bimetal element I29 so that the current bimetal element under these conditions operates just as quickly, that is to say, with the same time characteristic as an uncompensated current responsive bimetal element of the same composition. This is mainly due to the fact that there is insufficient time for any' substantial transfer of heat from the current bimetal to the ambient bimetal element.

It will be noted that the side plate of the frame I5 is provided with a circular opening I31 and the releasable supporting lever is also provided with an opening I39. The purpose of these openings will be explained in the description of the structure shown in Fig. 6.

Due to the presence of the connecting link 95, the circuit breaker structure shown in Fig. 5 is non-trip-free of the operating handle, that is to say, the circuit breaker may be closed and held closed against an overload current condition in the circuit by the handle H the same as in the case of the original embodiment of the invention.

If it is desired to make the circuit breaker trip-free of the operating handle "II, the circuit breaker structure is modified as shown in Fig. 6 by omitting the connecting link 95, and an additional angle-shaped lever MI is provided which is pivotally mounted on a pivot pin M3 supported in the pivot opening I39 of the releasable supporting lever. This angle-shaped lever engages a fixed stud I45 that is secured in the opening I31 in the side plate of the frame I5. The remaining structure of the breaker as shown in Fig. 6 is exactly the same as the circuit breaker structure shown in Fig. 5, and the corresponding parts have been given the same reference character. The circuit breaker shown in Fig. 6 is manually operated to open and closed position in the same manner as the previously described embodiments of the invention by moving the operating handle to "off or on position. When an overload of sufficient magnitude and duration occurs in the circuit controlled by the breaker, the bimetal trip element IUI deflects downwardly, effecting release of the supporting lever I25, whereupon the springs I3 actuate the supporting lever to the tripped position shown and cause movement of the switch member to open position. During the initial portion of the tripping movement of the lever I25, the angle-shaped lever MI is caused to be moved downwardly by reason of its engagement with the fixed stud I45, and this downward movement of the angle-shaped lever positively initiates opening movement of the switch member 65 and assists in moving the switch member downwardly until the line of action of the overcenter springs has been shifted below the pivot axis of the switch member, and also below the pivot axis of the operating lever 69. As the line of action of the springs is shifted below the pivot axis of the operating lever 69, the springs act to move the operating lever downwardly to the off position and the handle II upwardly toward the off position. The movement of these elements is arrested in an inter mediate position by the cam projection I21 striking the cross-pin 8| of the operating lever. Due

to the omission of the link 95, the contacts and switch member are trip-free of the operating handle, that is to say, opening of the contacts will take place even though an operator were to hold the operating handle in the on position when the breaker trips. This trip-free action results from the fact that upon tripping of the breaker, the line of action of the operating springs is shifted below the pivot axis 18 of the switch member 65 even though the handle is held in the on position. Before the breaker can be closed after a tripping operation, it is necessary to reset the releasabl supporting lever back to its latched position. This is accomplished in the Fig. 6 construction by moving the operating handle 'II from the intermediate indicating position shown, upwardly back to its off position. This movement of the operating handle causes the operating lever 69 to be moved downwardly to "ofi position, and during this movement the pin BI rides on the cam projection I21 and thereby forces the supporting lever back to its latched position where it is reengaged and held by the latch of the trip device II. ,After the breaker has been reset, it may be reclosed by moving the operating handle downwardly to the "on position.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details, arrangement of parts and combination of elements may be made without departing from some of the essential features of the invention. It is desired, therefore, that the language of the appended claims be given the broadest reasonable interpretation permissible in the light of the prior art.

We claim as our invention:

1. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising an operating member movable to an "on position to effect closing of said contacts, a spring biasing said contacts together when in said "on position, a normally restrained member biased by said spring to be operable when released to cause opening of said contacts, a trip device normally restraining said releasable member and operable in response to predetermined abnormal conditions to release said spring-biased member, said operating member having means engageable with said spring biased member to prevent operation of said spring biased member when said operating member is held in the on position.

2. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising an operating member movable to off and on positions to open and close said contacts. a spring operatively connecting the operating member and the movable contact for actuating contact member to open'and the movable contact, a trip spring and normally restrained in a fixed position, said trip member when released being actuated by said spring to cause automatic opening of said contacts, a trip device normally restraining said trip member and operable in response to predetermined abnormal conditions to release said trip member, said trip member remaining restrained in fixed position during normal opening and closing of said contacts, said operating member having means engageable with said trip member to prevent circuit opening operation of said trip member when said operating member is held in a predetermined position.

3. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising an oscillatable operating member movable to the "ofi and the "on positions for effecting opening and closing of said contacts, a spring biased member normally restrained in a fixed position and operable when released to cause automatic opening of said contacts, a trip device normally restraining said spring biased member and operable in response to predetermined overload conditions to release said member, said spring biased member remaining restrained in fixed position during normal opening and closing of said contacts, and a link connecting said operating member and said spring biased member, said link having a lost motion connection to one of said members to permit movement of said operating member to the on and the "off positions while said spring biased member is restrained in fixed position and said link acting to maintain said spring biased member in fixed position when I said operating member is held in the on posi tion.

4. A circuit breaker comprising a contact mem-- ber movable to open and closed positions, a support for supporting the said contact member, said support being movable when released to cause movement of the contact member to an open position, a trip device normally restraining the support in fixed position and operable in re sponse to predetermined abnormal conditions to release the support, an operating member movable to open and closed positions for operating the closed positions, and an operating spring connecting the operating member to the contact member, said operating member having means engageable with the support effective to restrain the support in fixed position when the operating member is held in closed position.

5. A circuit breaker comprising a contact member movable to open and closed positions, a normally restrained support for the contact member that is movable when released to cause movement of the conta t member to an open position, a trip device normally restraining said support in fixed position and operable in response to predetermined overload conditions to release said support, an oscillatable operating member movable to ofi and on positions for effecting operation of said contact member to open and closed positions, an overcenter operating spring connecting said operating member to said contact member for actuating said contact member and for actuating said support when the support is released, and a link providing a lost motion connection between said operating member and said support.

6. A circuit breaker having a switch member movable to open and closed circuit position, operating mechanism therefor comprising an operating member movable to on" and "oil positions member biased by said for operating said switch member to open and "tiered 'circ'uit positions, an overcenter operating spring operatively connecting said operating member and said switch member for actuating said switch member, a normally restrained releasable member operatively related to said switch member and operable by said spring when said member is released to cause movement of said switch member to an open circuit position, a trip device normally restraining said releasable memher in fixed position and operable in response to predetermined overload conditions to release said releasable member, and a link connecting said operating member and said releasable member effective to prevent tripping operation of said releasable member when said operating member is held in a predetermined position, said link having a pin and slot connection to one of said lastmentioned members to permit movement of said operating member to the on" and off positions while said releasable member is restrained in fixed position by the trip device.

'7. A circuit breaker having relatively movable contacts, operatin mechanism therefor comprising a pivotally mounted operating member movable to the off and the on positions for effecting opening and closing of said contacts, a releasabe member normally held in fixed position and operable when released to cause automatic opening of said contacts, means normally holding said releasable member in fixed position, said means being operable to release said member, and a connecting link pivotally connected to one of said members and having a lost motion connection with the other of said members, said operating member when moved to the on position following automatic opening operation of said contacts effecting resetting of said releasable member to its fixed position and closing of said contacts.

8. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising an operating member movable to the off" and the on positions to effect openin and closing of said contacts, a normally restrained spring biased member automatically operable upon the occurrence of predetermined abnormal conditions to cause opening of said contacts, a lever pivotally connected to said spring biased member, and means for moving said lever relative to said spring biased member for positively initiating opening of said contacts.

9. A circuit breaker having a switch member movable to open and to closed circuit positions, operating mechanism therefor comprising an operating member manually operable to the off and the on positions for effecting operation of said switch member to open and closed position, a normally restrained spring biased member automatically operable upon the occurrence of predetermined abnormal conditions to cause movement of said switch member to an open circuit position, and a lever pivotally connected to said spring biased member for positively initiating opening movement of said switch member both on manual and automatic opening operations of said breaker.

10." A circuit breaker having a switch member movable to open and to closed circuit positions, operating mechanism therefor comprisin an operating member manually operable to the off and the on positions for efiecting operation of said switch member to open and closed position, an operating spring operatively connecting said operating member and said switch member, a

normally restrained spring biased member automatically operable upon the occurrence of predetermined abnormal conditions in the circuit to cause movement of said switch member to an open circuit position irrespective of the position of said operating member, and a lever pivotally connected to said spring biased member for positively initiating movement of said switch member to open position upon operation of said spring biased member.

11. A circuit breaker having a switch member movable to open and closed circuit positions, operating mechanism therefor comprising an operating lever manually operable to the off and the on" positions for efiecting operation of said switch member to open and closed positions, an overcenter operating spring operatively connected to bias said operating member and said switch member, a sprin biased member normally restrained in one position and automatically operable upon the occurrence of predetermined abnormal conditions in the circuit to cause movement of said switch member to an open circuit position, and a lever connecting said operating member and said spring biased member and having a pin and slot connection with one of said members, said lever having a projection engageable with said switch member for positively initiating opening movement of said switch member.

12. A circuit breaker having relatively movable contact members, operating mechanism therefore comprising an oscillatable operating lever manually operable to off and the on positions to efiect opening and closing of said contact members, an operating spring operatively connected to bias said operating lever and the movable contact member, a normally re strained releasable member operatively related to the movable contact member and operable when released to cause automatic opening of said con tact members and movement of said operating lever to an intermediate position, and a trip device operable to release said releasable member, said operating lever when moved to the 011" position after an automatic opening operation of the breaker effecting resetting of said releasable member to its restrained position and closing of said contact members.

13. A circuit breaker having a switch member movable to open and to closed circuit positions, operating mechanism therefor comprising an oscillatable operating member movable to OE and the on positions to effect operation of said switch member to open and to closed position, an overcenter operating spring operatively connecting said operating member and said switch member, a pivotally mounted support member upon which said switch member is pivotally supported, a trip device having means normally restraining said support member in fixed position and operable in response to predetermined overload conditions to release said member, said support member when released causing automatic opening of said switch member and movement of said operatin member to an intermediate position, said operating member when moved to the on position following automatic opening operation of the breaker effecting both resetting of said support member and operation of said switch member to closed position.

14. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising an oscillatable operating member movable to off and the on positions to effect opening and closin of said contacts, a normally restrained releasable member operable when released to cause said mechanism to automatically open said contacts and move said operating member to an intermediate position, a trip device normally restraining said releasable member and operable in response to predetermined overload conditions to release said member, said operating member when moved from said intermediate position to said off position being operative to reset said releasable member to its restrained position and being operable when moved from said intermediate position to said on position to effect both resetting of said releasable mem her and closing of said contacts.

15. A circuit breaker having a switch member movable to open and to closed circuit positions, operating mechanism therefor comprising an oscillatable operating member movable to "01? and the on positions to effect operation of said switch member to open and to closed position, an overceiiteroperating spring operatively relatin said operating member to said switch member, a normally restrained releasable member operatively related to said switch member and operable when released to cause said mechanism to effect automatic circuit opening operation of said switch member and movement of said oper ating member to an intermediate position, a trip device having means normally restraining said releasable member and operable in response to predetermined abnormal current conditions to release said member, said operating member having means engageable with said releasable member whereby movement of said operating member from said intermediate position to said off position resets said releasable member to its restrained position and movement of said operating member from said intermediate position to said on position also resets said releasable member in addition to operating said switch member to the closed position.

16. A circuit breaker comprising a base of insulating material, contact means including a movable contact member mounted on said base, operating mechanism therefor mounted on said base comprising a pivoted operating lever, an overcenter operating spring operative to bias said operating lever and said contact member, a normally restrained releasable member operable when released to cause automatic opening operation of said contact means, a cover removably mounted on said base, an operatin handle oscillatably mounted on the front of said cover and having a bifurcated portion engaging said operating lever to provide a separable operative connection between the handle and lever.

17. A circuit breaker having a switch member movable to open and closed circuit positions, operating mechanism therefor comprising an oscillatable operating member having a handle movable to oil and on positions for effecting operationof said switch member to open and to closed circuit positions, an overcenter operating spring operatively relating said operating member to said switch member, a normally restrained releasable member operatively related to said switch member and operable to a tripped position when released to cause said mechanism to automatically move said switch member to an open circuit position and move said operating member to the off position, a casing for enclosin said parts except the handle portion of said operating member which projects through an opening in the front wall of said casing, and

17 a trip indicating element mounted in the front wall of said casing and engaged and moved to an indicating position by said releasable member upon release thereof.

18. In a circuit breaker having relatively movable contacts and operating mechanism therefor, a trip device comprising a pivotally mounted bimetal trip element heated in response to the current of the circuit and deflectable when heated a predetermined amount by overload current to effect tripping of said circuit breaker operating mechanism, an ambient t mperature responsive bimetal element for compensating said current responsive bimetal element for changes in ambient temperature, said ambient temperature responsive bimetal element being mounted on a fixed support at one end, and a metallever connecting the pivot end of the current responsive bimetal element ment.

able contacts and operating mechanism therefor, a trip device comprising a pivotally mounted bimetal trip element heated in response to the current of the circuit and deflectable when heated a predetermined amount by overload current to effect tripping of said circuit breaker operating mechanism, an ambient temperature responsive bimetal element for compensating said current responsive bimetal element for changes in ambient temperature, said ambient temperature responsive bimetal element being mounted on a fixed support sponsive bimetal element to the of said ambient temperature responsive bimetal element, and an adjusting screw engaging said ambient temperature responsive bimetal element for adjusting the minimum trip current setting of said trip device.

20. In a circuit breaker having relatively movable contacts and operating mechanism therefor, a trip device comprising a pivotally mounted bimetal trip element heated in response to 45 the current 'of the circuit and deflectable when heated a predetermined amount by overload current to effect tripping of said circuit breaker operatin mechanism, an ambient temperature to the free end portion or said ambient temperature responsive bimetal elego 1 operable upon the occurrence at one end, a metal lever connecting the pivot end of the current refree end portion portion of said ambient meeting the pivot end of the current responsive bimetal element to the free end portion of said ambient temperature responsive bimetal element, said connecting lever having a bent portion provided with a slot engaging the free end portion of said ambient temperature responsive element.

22. In a. circuit breaker having relatively mov able contacts and operating mechanism therefor, a trip device comprising a pivotally mounted bimetal trip element heated in response to the current of the circuit and deflectable when heated a. predetermined amount by overload current to effect tripping of said circuit breaker operating mechanism, an ambient temperature responsive bimetal element for compensating said current responsive bimetal element for changes in ambient temperature, said ambient temperature responsive bimetal element being mounted on a hired support at one end, and a metal lever connecting the pivot end of the cur- ;rent responsive bimetal element to the free end temperature responsive bimetal element, said lever engaging an adjusting screw threadedly supported in the ambient temperature responsive bimetal adjacent the free end thereof.

23. A circuit breaker having relatively movable contacts, operating mechanism therefor comprising an operating member movable to the off and .the on positions to effect opening and closing of said contacts, a normally restrained spring biased member automatically of predetermined abnormal conditions to cause opening of said contacts, and a lever operatively connected be" tween said normally restrained spring biased member and a fixed point so thatmovement of said spring biased member upon the occurrence of said predetermined abnormal "conditions causes movement of said lever relative thereto ior positively prying said contacts open.

24. A circuit breaker having a switch member movable to open and to closed circuit positions, operating mechanism therefor comprising an operating member manually operable to the off and the "on positions for effecting operation of said switch member to open and closed position, an operating spring operatively connecting said operating member and said switch member, a

responsive bimetal element f compensating said normally restrained spring biased member autocurrent responsive bimetal element for changes in ambient temperature, said ambient temperature responsive bimetal element being mounted on a fixed support at one end, a lever connecting matically operable upon the occurrence of predetermined abnormal conditions in the circuit to cause movement of said switch member to an open circuit position irrespective of the position the pivot end of the current responsive bimetal of Said operating member, and a lever having a element to the free end portion of said ambient slidable engagement with said normally restrained spring biased member for prying said switch member and positively initiating movement thereof to open position upon operation of for moving said ambient said spring biased member.

25. An electric switch having a, manually operated member movable between positions corresponding to switch open and switch closed positions, mechanism operated thereby including a for, a trip device comprising a pivotally mounted spring for permitting opening and closing of the bimetal trip element heated in response to the current of the circuit and deflectable when heated a predetermined amount by overload current to effect tripping of said circuit breaker operating switch, electro-responsive means for effecting opening of the switch, and means selective at will to permit the opening of said switch by the spring in response to said electro-responsive mechanism, an ambient temperature responsive means ith d 1 t t associated movement of said manual operating member.

26. An electric switch having switch operating mechanism including an operating handle movable between positions corresponding to switch open and switch closed positions for moving Said bimetal element for compensating said current responsive bimetal element for changes in ambient temperature, said ambient temperature responsive bimetal element being mounted on a fixed support at one end, and a metal lever conmechanism manually into and out of said posi-,

dependently of movement of said handle into 10 switoh open position.

HARLAN s. GANG.- GERALD J. FREESE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,810,861 U'llrich June 16, 1931 ,6 0, 13 De Ville Dec. 7, 1926 1,829,037

Bobrofi Oct. 27, 1931 

